This invention relates to recording devices, particularly for recording speeds.
In such devices, a recording sheet or other medium is moved in one direction, and a pen or other recording instrument shifts, a distance dependent on the speed being recorded, in a direction transverse to the sheet movement. In order to obtain recordings that may be properly evaluated, it is desirable that the instrument moves along an absolutely straight line over a relatively wide recording range. Known straight line motion mechanisms have hitherto not been particularly useful.
Such known recording apparatuses, of the type used in tachographs, involve a slide which carries a recording instrument mounted with at least three bearings on two guide bars. This kind of mounting results in a rather expensive device because the guide bars must be exactly parallel and the bearings sliding thereon must have as little play as possible. This is necessary to avoid skewing and winding of the slide. On the other hand, this structure introduces a substantial amount of friction with which the instrumentality must somehow cope.
In such devices, pressure actuated pin shaped recording instruments are mounted to be axially slidable along the shaft in a bracket arranged on the slide. This results in complexities and production difficulties, as well as high expenses, and subjects the device to the risk of failure. Since the friction resulting from the recording process is directed transverse to the direction of the spring action on the recording instrument, there is always the risk of the recording device being stuck on the guides. By contrast, a recording instrument which is fastened to a leaf spring mounted on the slide, exhibits no decisive advantages, either during production or thereafter, because achieving the desired recording pressure involves a substantial amount of adjustment.
An object of the invention is to avoid these disadvantages.
Another object of the invention is to improve devices of this type.